Method of machining wafer

Abstract

A method of machining a wafer in which, at the time of grinding the back-side surface of the wafer, only a back-side surface region corresponding to a device formation region where semiconductor chips are formed is thinned by grinding, to form a recessed part on the back side of the wafer. An annular projected part surrounding the recessed part is utilized to secure rigidity of the wafer. Next, the recessed part is etched to cause metallic electrodes to project from the bottom surface of the recessed part, thereby forming a back-side electrode parts, then an insulating film is formed in the recessed part, and the insulating film and end surfaces of the back-side electrode parts are cut.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method of machining a wafer in a process in which devices such as semiconductor chips provided with metallic electrodes penetrating therethrough are obtained from the wafer provided with a plurality of the devices.[0003]2. Description of the Related Art[0004]In the semiconductor device technology in recent years, stack type semiconductor packages in which a plurality of semiconductor chips such as MCPs (multi chip packages) and SIPs (system in packages) are stacked have been utilized effectively for achieving a higher density, a smaller size and a thinner form. Methods for manufacturing such a semiconductor package includes a method in which semiconductor chips are stacked on a package substrate called “interposer”, the electrodes of the interposer and the semiconductor chips are, or the electrodes of the plurality of semiconductor chips stacked are, electrically connected through meta...

AI Technical Summary

Benefits of technology

The present invention provides a method for machining a wafer by which the rigidity of the wafer is secured during manufacturing processes, making it easy to handle and smoothly transfer between processing steps. The method includes steps of protecting the wafer with a protective tape, thinning the back-side surface of the wafer to form a recessed part, and coating the recessed part with an insulating film to form an insulating film. The method also includes steps of etching the recessed part to remove any damage, and flattening the insulating film and back-side electrode parts for better contact with other components. The wafer can then be transferred to a splitting step for individual device formation. The method improves productivity and yield of the device.

Problems solved by technology

In this method, however, the connection using the metallic wires has a problem in which the metallic wires may be deformed at the time of pouring a molding resin, to cause line breakage or short-circuit, or air remaining in the molding resin expands at the time of heating, to result in breakage.

However, since the semiconductor wafer is processed to a very small thickness for reductions in size and thickness as above-mentioned, it is difficult to suitably handle the semiconductor wafer in transfer to an etching step after the thinning or in transfer to the subsequent splitting step, and the semiconductor wafer is susceptible to cracking, so that the yield thereof is lowered.

However, in the case where, for example, the spin coating technique in general use as a method for forming an insulating film is adopted for forming the insulating film in this instance, the resin flows over top portions of the electrodes, resulting in that the electrodes might be covered with the resin, possibly leading to failure in conduction.

Thus, the disclosed method is supposed to be impractical because it is difficult with the method to apply the resin to the back side of the wafer in a predetermined thickness in such a manner as to retain the condition where the top portions of the electrodes are exposed.

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